SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '90c4a3de0c4d9ed915aa07193a2f29a2394d8ea526d131c2f0e1f377b4f0baab' 
  AND token = 'Lt0RIjtJbBAbAxM846R3koWgogItlLOjXSUf5ytCPjY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}